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Murder charges have been filed against Christopher Dorner, the fugitive fired Los Angeles police officer wanted for three slayings in a deadly revenge plot targeting law enforcement agents and their families. If apprehended and convicted, he could face the death penalty.

The Riverside County District Attorney's office on Monday announced that it has filed a murder charge against Dorner in the shooting death of Riverside police officer Michael Crain. Dorner is also wanted in connection with, but has not yet been charged with, the daughter of a former police department captain and her fiancé.

$1 Million Reward Offered in Hunt for Dorner

Los Angeles authorities announced a $1 million reward leading to the capture Christopher Dorner, suspected in the fatal shootings of three people, including a police officer, in an alleged revenge plot. NBC4's Jane Yamamoto reports for the NBC4 News at 6 p.m. on Sunday, Feb. 10, 2013. (Published Monday, Feb 11, 2013)

The murder charge includes two special-circumstance allegations — the murder of a peace officer and the discharge of a firearm from a vehicle — that make Dorner eligible for the death penalty. Dorner was also charged with three counts of attempted murder of a peace officer.

"Mr. Dorner has committed one of the most horrific crimes imaginable," Riverside County District Attorney Paul Zellerbach said as he announced the charges Monday.

Caught on Video Tossing Items, Dorner "Looked Really Calm"

Store manager Majid Yahyai said when his employee went to throw out of the trash, he discovered a magazine clip filled with bullets, a military belt and a helmet. A man matching the description of LAPD manhunt suspect Christopher Dorner was caught on surveillance camera tossing the items into a dumpster behind Yahyai s store 12 hours after he's suspected of killing a couple in Irvine. Kim Baldonado reports from Buena Park for the NBC4 News at 11 p.m. on Feb. 9, 2013. (Published Monday, Feb 11, 2013)

Crain, 34, was shot Thursday while he and his 27-year-old trainee partner — with less than a year on the job — were sitting at a traffic light near the Riverside Freeway in an ambush. The trainee was also injured in what police described as an ambush-style shooting.

Ex-LAPD Officer Wanted in Shootings

Earlier Monday, the Los Angeles Police Department said law enforcement agencies involved in the search for Dorner are following up on more 600 tips from the public in an investigation that includes a $1 million reward.

At a Monday morning news conference, Los Angeles Police Department Lt. Andy Neiman said the clues were related to possible sightings and other information regarding the location of 33-year-old Dorner, accused of killing daughter of a former LAPD captain and her fiancé Feb. 3 before Thursday's shooting death of a Riverside police officer.

Dorner outlined his plans for a revenge plot targeting law enforcement agents and their families in an 11,400-word document posted online, according to investigators.

"We will follow up on every clue we receive," Neiman said. "We have to prioritize. Obviously, 600 clues is a lot to sort through. Those will be followed up on immediately, others maybe not quite as readily."

Neiman was asked whether he thought the leads were generated by the $1 million reward announced Sunday for information leading to the arrest and conviction of Dorner, a former Navy reservist who was fired from the LAPD in 2008.

"It's my hope the public would do everything they can," Neiman said. "If the million dollar reward is stimulating additional clues, all the better."

A second LAPD briefing on the case is scheduled for 6 p.m. ET.

Every day that Dorner is loose, said LAPD Chief Charlie Beck on Sunday as he announced the huge reward, is another day when the likelihood of an attack on police officers or their families increases.

"We are asking the public, 'Please help us to protect you,'" Beck said at a news conference. "Please help us to find Dorner before he is able to kill again."

As for search locations, teams on the ground and in the air continued the manhunt Monday in the Big Bear area. Dorner's burned-out Nissan Titan pickup was found south of Big Bear Lake Thursday, just hours after the "ambush-style" shooting death of Riverside Officer Michael Crain.

There have been no reported sightings of Dorner in the Big Bear area, but authorities still consider the San Bernardino Mountain resort community a "critical" location in the investigation. Agents are searching vacation homes and government lease cabins in remote areas.

Dorner was identified Wednesday as a suspect in the Feb. 3 shooting deaths of Monica Quan, 28, and her fiancé, Keith Lawrence, 27. Dorner repeatedly refers to Quan's father as being involved in his 2008 firing from the LAPD.

Hours after the announcement, LAPD officers providing a security detail for one of the subjects mentioned in Dorner's manifesto encountered him early Thursday in Corona. About 20 minutes later, Crain and his partner were "ambushed" by Dorner in Riverside, authorities said.

Chief Charlie Beck said Sunday that the LAPD plans to reopen the case involving Dorner's firing after he reported another officer for alleged brutality. Investigators later said Dorner's accusation was false.